Car sputtering, engine light flashing

[CB88]

I have a 2006 Corolla CE. Last night, while driving, the car started sputtering and the engine light was blinking.
I had it towed to a mechanic and he wants to start by changing the ignition coils, and will keep working from that.
He is charging 400 for that ($125 diagnosis) then he said that it thinks it will run up to $735 but he won't tell me what parts he would be changing for that cost, which worries me. I am a woman and learning as much as possible as I go along. This is my only transportation and I have been researching this issue, and it seems that this is a complicated issue, but I would appreciate any guidance about this, specially mechanically.
Previous to the sputtering issue, the car gave a code PO 171, which I was told it still has. I had the oxygen sensor replaced as well as the Mass Air Flow sensor but it did not make a difference. Once a mechanic cleaned the area of the fuel injectors (which were all replaced at the time a few years ago), and the code went away, but then it came back a few months later. The code also disappeared when I parked the car nose up, and reappeared when I took a turn and the car was tilted to the right. Maybe that was due to the Oxygen sensor which I was told was broken, but as I mentioned earlier, replacing it made no difference. I am just worried on spending money on this car for nothing if it ends up costing thousands as I won't be able to keep it.
Please advice me on what I have to look for and what I should be careful about. Thank you

 

[The Critic]

It sounds like you have a legitimate misfire and a mechanic who wants to fire the parts cannon.

Find a new mechanic.

 

[bullwinkle]

It could be as simple as a cracked vacuum hose-the mechanic needs to start checking things a little more thoroughly & stop chucking parts at it. Odds of all 4 coils failing at once are basically ZERO-plus you would have misfire codes, not a lean running air-fuel ratio code. Good luck!

 

[The Critic]

It wouldn’t surprise me if the car needed all new injectors, but since a lot of previous work has been done (with unknown parts quality), this can become a complicated and expensive mess.

 

[Passport1]

PO171 code can be a vacuum leak, dirty injectors, dirty maf, fuel pump regulator or fuel pump problem. Ask you mechanic to do a proper Dx before your Corolla gets the parts 'cannonade'. A can of Techron in the gas might fix it. BTW I'm dealing with this exact issue on my '06 Suzuki right now.

 

[CB88]

Thank you for the suggestions.
The mechanic said that there were 2 coils from an unknown cheap brand, and he wanted to replace these two.
He added that the car sputtering and the engine light flashing were unrelated. He was first going to fix the sputtering by changing the coils, and then address the engine light flashing, which raised my suspicion.

 

[CB88]

It could be as simple as a cracked vacuum hose-the mechanic needs to start checking things a little more thoroughly & stop chucking parts at it. Odds of all 4 coils failing at once are basically ZERO-plus you would have misfire codes, not a lean running air-fuel ratio code. Good luck!

Thank you. He added that the car misfiring and the engine light flashing were unrelated, and that he would first change 2 coils, and after that would try to figure out why the engine light was flashing. This seemed strange to me.

 

[Dinoburner]

Not sure what diagnosis will show a need to change all 4 ignition coils then coming up with with a final cost. Might that be his boat payment? Having a symptom of nose up effect and turning has me wanting to start with the fuel system. Good Luck

 

[SC Maintenance]

You either don't have all the data, or the mechanic just wants to fire the parts canon.

CEL won't flash from a P0171 alone - its a misfire. What Pxxxx code - P0300 or P030x?

If its multiple misfire its not a coil. If its one cylinder he can swap coils or change at most 1 and see if it goes away. Firing a coil parts canon is illogical.

What is your long term fuel trim? What other codes? What is your MAF reading at idle - should roughly match cubic inches.

I agree its likely a vacuum leak that got worse.

 

[gabriel9766]

Thank you. He added that the car misfiring and the engine light flashing were unrelated, and that he would first change 2 coils, and after that would try to figure out why the engine light was flashing. This seemed strange to me.

Engine light only flashes because of a misfire. You need to find a new mechanic before you get ripped off.

 

[CB88]

It sounds like you have a legitimate misfire and a mechanic who wants to fire the parts cannon.

Find a new mechanic.

Sounds right. I am having the car towed to a different mechanic. Thanks

 

[CB88]

Engine light only flashes because of a misfire. You need to find a new mechanic before you get ripped off.

Thank you. I don't know much, but this seemed very weird.

 

[Passport1]

Thank you. He added that the car misfiring and the engine light flashing were unrelated, and that he would first change 2 coils, and after that would try to figure out why the engine light was flashing. This seemed strange to me.

BTW, welcome to the internet center of automotive mechanical wizardry. Lots of plausible advice already offered. Just keep in mind Occam's Razor is usually the best and least expensive advice.

Dave Schoenbeck

 

[CB88]

Engine light only flashes because of a misfire. You need to find a new mechanic before you get ripped off.

Thanks for the tip.

 

[CB88]

BTW, welcome to the internet center of automotive mechanical wizardry. Lots of plausible advice already offered. Just keep in mind Occam's Razor is usually the best and least expensive advice.

View attachment 261980
Dave Schoenbeck

Thanks. Yes of course, the simplest way is the best, but greed dictates otherwise.

 

[Leo99]

I hate this. Coils throw a specific code for each coil when they misfire. You switch the coils around to see if the code follows the coil or stays with the cylinder. I had the same code P0171 on my old Corolla. It was the intake manifold gasket. The OEM gasket was not the best type of rubber and they dry out and cause a leak. They cost about $5 or $10 and take about 30 minutes to change. Less time for a professional.

Where are you located?

 

[CB88]

I hate this. Coils throw a specific code for each coil when they misfire. You switch the coils around to see if the code follows the coil or stays with the cylinder. I had the same code P0171 on my old Corolla. It was the intake manifold gasket. The OEM gasket was not the best type of rubber and they dry out and cause a leak. They cost about $5 or $10 and take about 30 minutes to change. Less time for a professional.

Where are you located?

I am in Los Angeles. I hate this too, because I didn't just choose the first guy down the block. I followed a referral from a friend. Feels like I have stepped into the wolves' den.

 

[D60]

Also maybe ask your next mechanic if he has a smoke machine. If he gives you a blank stare, keep going.

That said, I'm not sure your 0171 is related to your misfires (but could be). Ask the next mechanic for the exact codes. A P0300 can be problematic but if there are specific cylinders cited (0301 to 0304) that's a starting place.

And as stated the CEL only flashes for misfires and this will often cause sputtering or bucking when occurring. If someone told you the two are unrelated that is ........ troubling. They may need a diagnostic themselves, likely revealing a P0-IDIOT

 

[GSCJR]

I had the same code P0171 on my old Corolla. It was the intake manifold gasket.

This is what I would have investigated first.

 

[CB88]

This is what I would have investigated first.

Thank you